Transfusing for hemoglobin concentrations <7.5 g/dL, rather than liberally when levels dropped <9.5 g/dL in the ICU or <8.5 g/dL outside the ICU, was noninferior for the composite of death from any cause, MI, stroke, or new-onset renal failure with dialysis within 6 months of surgery (17.4% vs 17.1%, OR 1.02, P=0.006 for noninferiority).

Six-month mortality was similar between arms too (6.2% vs 6.4%, OR 0.95, 95% CI 0.75-1.21), according to C. David Mazer, MD, of St. Michael's Hospital in Toronto, and colleagues.

"Over the past number of years, surgical practice has become increasingly restrictive in terms of transfusion because of concerns about both short- and long-term risks," said Michael Mack, MD, medical director of Cardiovascular Surgery at Baylor Health Care System in Plano, Texas.

While the study does support that the liberal strategy was safe too, the message is still that "all other things being equal, if the patient is doing fine, don't transfuse to a number," Mack, who was not involved in the study, told MedPage Today.

TRICS (Transfusion Requirements in Cardiac Surgery) III was more than twice as big as TITRe2 and twice as long, with 5,243 adults getting cardiac surgery with cardiopulmonary bypass randomized open-label to transfusion strategy. All were at moderate- to-high predicted risk for death, as defined by an additive European System for Cardiac Operative Risk Evaluation (EuroSCORE) I score of ≥6 on the 47-point scale.

During the operation and up to 28 days afterward, the protocol mandated red cell transfusions for hemoglobin levels <7.5 g/dL in the restrictive strategy arm and <9.5 g/dL in the ICU or <8.5 g/dL in the non-ICU ward for the liberal strategy group. Patients unable or unwilling to receive blood products were excluded.

Aside from safety on the primary endpoint, an expanded composite adding hospital readmission, emergency department visit, or coronary revascularization likewise came out similar between restrictive and liberal thresholds (43.8% vs 42.8%, OR 1.04, 95% CI 0.93-1.17) as did the individual components.

In those ages ≥75, the restrictive strategy was actually superior, while younger patients had a lower risk with the liberal strategy. That finding was robust across sensitivity analyses and when adjusted for other variables.

"The findings in patients 75 years of age or older appear to contradict the current practice, in which a liberal transfusion strategy is used in older patients undergoing cardiac or noncardiac surgery who thus receive more red cell transfusions than do younger patients," the researchers noted. "One could hypothesize that older patients may have unacceptable adverse effect related to transfusion (e.g., volume overload and inflammatory and infectious complications) or that there may be age-related differences in the adverse-effect profile of transfusion or anemia. Although not significant, the direction of this finding was also present in the TITRe2 trial."

Mack agreed that it should provide "reassurance and comfort" for the physician, and the constellation of other providers who may be in the care pathway that leads to transfusion in the older population. "You don't have to transfuse at 8.5 in a patient just because they're 80," he said.

The researchers acknowledged the possibility of bias due to the open-label design but noted that sensitivity analyses were consistent with the primary analysis, suggesting "robust" results. Another limitation was use of various sources for outcome data, including telephone contact, hospital records, and database registries.

The trial was supported by the Canadian Institutes of Health Research (CIHR), the Canadian Blood Services-Health Canada, the National Health and Medical Research Council of Australia, the Health Research Council of New Zealand, and by the CIHR Canada Research Chairs Programme.

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